If a covalent bond is polar:

• A. Electrons are not shared by atoms.
• B. Protons are shared by atoms.
• C. The bond is not important to living cells.
• D. One of the atoms has a partial negative charge.
• E. The bond is not a strong bond.

Answer: (D)

Verified step by step guidance

1. Understand that a covalent bond involves the sharing of electrons between atoms. In a polar covalent bond, the electrons are shared unequally.
2. Recognize that in a polar covalent bond, one atom will attract the shared electrons more strongly than the other, leading to a partial negative charge on that atom.
3. Identify that the atom with the stronger electronegativity will have a partial negative charge, while the other atom will have a partial positive charge.
4. Acknowledge that polar covalent bonds are important in biology because they contribute to the formation of molecules with distinct polar regions, which can affect molecular interactions and solubility.
5. Note that while polar covalent bonds are not as strong as ionic bonds, they are still significant in the structure and function of biological molecules.